In order to avoid interference between adjacent cells, a conventional FDMA or TDMA-based cellular system may obtain a significant signal to interference ratio when the adjacent cells use no common resource. However, when the adjacent cells use no common resource, the frequency reuse efficiency is decreased. The conventional cellular system has a primary aim to provide a voice service of which a data rate is practically constant. Accordingly, it is effective for the cellular system to increase the number of available channels having the significant signal to interference ratio by means of power control so as to have increased system capability. Accordingly, a CDMA-based voice system that largely increases the frequency reuse efficiency has spread. The CDMA-based voice system allows a large of channels to have appropriate interference by decreasing a range of fluctuation of the respective channel interference amount through interference averaging.
However, as a communication service is converted from a voice service of a constant data rate to a packet service of a changeable data rate, it is known that it is not optimal to maintain the appropriate interference by the interference averaging. Also, as orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiplexing access (OFDMA) technologies in which it is easy to avoid interference have been developed in cellular areas, an interference processing problem of adjacent cells has again occurred.
In order to solve the interference processing problem of the adjacent cells in the OFDM/OFDMA-based cellular environment, a method for averaging the interference by a frequency hopping method has been developed. According to this method, the respective base stations average the interferences of the adjacent cells by using different hopping patterns in every cell.
In order to solve the interference processing problem of the adjacent cells in the OFDM/OFDMA-based cellular environment, another method for averaging interferences by the frequency hopping is disclosed in Korean Patent Laid-Open Publication No. 2005-0048261 (“A resource spatial vision, a physical channel allocation, and a power allocation method in orthogonal frequency division multiplexing access (OFDMA)-based cellular system, and a frequency reuse efficiency using the same”, ETRI, 2005.5.24.). In an exemplary embodiment of this method, all cells are divided into three frequency reuse patterns, and one resource space is divided into three resource sub-spaces. In order to have less effect on the adjacent cells, the respective cells allow the terminal to perform high-power communication by using one of the three resource sub-spaces and to perform low-power communication by others thereof. That is, while a cell-border terminal of a bad channel state communicates as a frequency reuse coefficient 3 using ⅓ of the entire resource, a base station?near terminal of a good channel state communicates without having a large amount of interference on the adjacent cells.
A method for increasing a frequency reuse coefficient for the cell-border terminal was disclosed by Siemens in the 3GPP conference (R1-050599, Siemens, “Interference mitigation considerations and results on frequency reuse,” 3GPP RAN WG1 Ad Hoc on LTE, Sophia Antipolis, France, June 2005). According to this method, inter-cell terminals commonly use some resources, and the cell-border terminal equally divides other resources into 3 and uses one thereof. However, this method is not effective with regard to resource efficiency.
Particularly, according to the communication resource allocation method of the base station described above, the base station continuously allocates some specified communication resource to the terminal, and accordingly the terminal have a loss of a diversity gain. Also, the communication resource allocation method described above may not solve inter-cell resource request imbalance content.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.